Classifications

• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
  • G06T7/00—Image analysis
  • G06T7/0002—Inspection of images, e.g. flaw detection
  • G06T7/0012—Biomedical image inspection
  • G06T7/0014—Biomedical image inspection using an image reference approach
• • G—PHYSICS
  • G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
  • G16H—HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA
  • G16H50/00—ICT specially adapted for medical diagnosis, medical simulation or medical data mining; ICT specially adapted for detecting, monitoring or modelling epidemics or pandemics
  • G16H50/30—ICT specially adapted for medical diagnosis, medical simulation or medical data mining; ICT specially adapted for detecting, monitoring or modelling epidemics or pandemics for calculating health indices; for individual health risk assessment
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/0033—Features or image-related aspects of imaging apparatus, e.g. for MRI, optical tomography or impedance tomography apparatus; Arrangements of imaging apparatus in a room
  • A61B5/004—Features or image-related aspects of imaging apparatus, e.g. for MRI, optical tomography or impedance tomography apparatus; Arrangements of imaging apparatus in a room adapted for image acquisition of a particular organ or body part
  • A61B5/0044—Features or image-related aspects of imaging apparatus, e.g. for MRI, optical tomography or impedance tomography apparatus; Arrangements of imaging apparatus in a room adapted for image acquisition of a particular organ or body part for the heart
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration or pH-value ; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid or cerebral tissue
  • A61B5/14535—Measuring characteristics of blood in vivo, e.g. gas concentration or pH-value ; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid or cerebral tissue for measuring haematocrit
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/74—Details of notification to user or communication with user or patient; User input means
  • A61B5/7475—User input or interface means, e.g. keyboard, pointing device, joystick
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
  • G06T7/00—Image analysis
  • G06T7/10—Segmentation; Edge detection
• • G—PHYSICS
  • G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
  • G16H—HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA
  • G16H10/00—ICT specially adapted for the handling or processing of patient-related medical or healthcare data
  • G16H10/60—ICT specially adapted for the handling or processing of patient-related medical or healthcare data for patient-specific data, e.g. for electronic patient records
• • G—PHYSICS
  • G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
  • G16H—HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA
  • G16H50/00—ICT specially adapted for medical diagnosis, medical simulation or medical data mining; ICT specially adapted for detecting, monitoring or modelling epidemics or pandemics
  • G16H50/50—ICT specially adapted for medical diagnosis, medical simulation or medical data mining; ICT specially adapted for detecting, monitoring or modelling epidemics or pandemics for simulation or modelling of medical disorders
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
  • G06T2207/00—Indexing scheme for image analysis or image enhancement
  • G06T2207/20—Special algorithmic details
  • G06T2207/20081—Training; Learning
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
  • G06T2207/00—Indexing scheme for image analysis or image enhancement
  • G06T2207/30—Subject of image; Context of image processing
  • G06T2207/30004—Biomedical image processing
  • G06T2207/30048—Heart; Cardiac

Definitions

• the following generally relates to imaging and more particularly to fractional flow reserve simulation (FFR) customization, calibration and/or training, and is described with particular application to FFR - computed tomography (FFR-CT), and is also amenable to x-ray FFR.
• FFR fractional flow reserve simulation
• Fractional flow reserve is an invasive measure in the catheterization laboratory (Cath Lab) to quantify, via an FFR index, the hemodynamic significance of a coronary lesion due to calcified or soft plaque.
• the index indicates the functional severity of a coronary stenosis that is calculated from pressure measurements made during coronary arteriography and is defined as the distal blood pressure (behind a stenosis) relative to the proximal pressure (close to the ostium) under hyperemic conditions. That is, the FFR index expresses the maximal flow down a vessel in the presence of a stenosis compared to the maximal flow in the hypothetical absence of the stenosis.
• the FFR value is an absolute number between 0 and 1, where a value 0.50 indicates that a given stenosis causes a 50% drop in blood pressure.
• An invasive FFR procedure requires insertion of a catheter into the femoral or radial arteries and advancement of the catheter to the stenosis where a sensor at the tip of the catheter senses pressure across the stenosis, during conditions promoted by various agents that effect vessel geometry, compliance and resistance, and/or other characteristics.
• a non-invasive approach estimates an FFR index from CT image data of the heart (e.g., from contrast enhanced coronary computed tomography angiography, CCTA) through computational fluid dynamic (CFD) simulations in which blood flow and pressure through the coronaries are simulated. This includes using CCTA image data to derive a geometrical model of the coronary tree, extract features therefrom, and determine boundary conditions from the features for the simulation.
• CT image data of the heart e.g., from contrast enhanced coronary computed tomography angiography, CCTA
• CFD computational fluid dynamic
• FFR-CT simulation software has been deployed at a clinical site with pre- set, factory-tuned algorithm parameters, e.g., for segmentation of the coronaries from the CCTA image, or scaling factors for peripheral resistances which control the simulated flow of blood through the coronaries.
• algorithm parameters e.g., for segmentation of the coronaries from the CCTA image, or scaling factors for peripheral resistances which control the simulated flow of blood through the coronaries.
• usage patterns, individual habits, and/or patient populations may vary from site to site. For example, when segmenting a vessel, one clinician may segment inside an inside surface of a vessel wall, while another clinician segments on the vessel wall. In another example, the actual perimeter of the vessel wall may be clearer in a higher image quality image relative to a lower the image quality image. As a result, an accuracy of FFR-CT simulation results may vary from clinician to clinician, site to site, etc.
• a computing system includes a computer readable storage medium with computer executable instructions, including a biophysical simulator with a segmentor and a boundary condition determiner.
• the computing system further includes a processor configured to execute the biophysical simulator to compute a fractional flow reserve index with cardiac imaging data and at least one of an adapted coronary tree segmentation and an adapted boundary condition.
• a computer readable storage medium is encoded with computer readable instructions, which, when executed by a processor of a computing system, causes the processor to: receive cardiac imaging data, and execute a biophysical simulator to compute a fractional flow reserve index with the cardiac imaging data and at least one of an adapted coronary tree segmentation and an adapted boundary condition.
• a method in another aspect, includes receiving cardiac imaging data, and computing a fractional flow reserve index with the cardiac imaging data and at least one of an adapted coronary tree segmentation and an adapted boundary condition.
• the invention may take form in various components and arrangements of components, and in various steps and arrangements of steps.
• the drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention.
• FIGURE 1 schematically illustrates a system, including a computing system and an imaging system.
• FIGURE 2 illustrates an example biophysical simulator.
• FIGURE 3 illustrates an example segmentation of the coronary arteries.
• FIGURE 4 illustrates an example anatomical model of the coronary arteries.
• FIGURE 5 illustrates an example method in accordance with an embodiment herein.
• FIGURE 6 illustrates another example method in accordance with an embodiment herein.
• FIGURE 7 illustrates another example method in accordance with an embodiment herein.
• FIGURE 1 schematically illustrates a system 100 including an imaging system 102 such as a CT scanner.
• the system 100 includes an x-ray imager.
• the imaging system 102 includes a generally stationary gantry 104 and a rotating gantry 106, which is rotatably supported by the stationary gantry 104 and rotates around an examination region 108 about a z-axis.
• a subject support 110 such as a couch, supports an object or subject in the examination region 108.
• a radiation source 112 such as an x-ray tube, is rotatably supported by the rotating gantry 106, rotates with the rotating gantry 106, and emits radiation that traverses the examination region 108.
• a radiation sensitive detector array 114 subtends an angular arc opposite the radiation source 112 across the examination region 1088.
• the radiation sensitive detector array 114 detects radiation traversing the examination region 108 and generates an electrical signal(s) (projection data) indicative thereof.
• a reconstructor 116 reconstructs the projection data, generating volumetric image data indicative of a scanned portion of a subject or object located in the examination region 108.
• a computing system 118 serves as an operator console.
• the console 118 includes a processor 120 (e.g., a microprocessor, a central processing unit, etc.) and a computer readable storage medium 122, which excludes transitory medium, and includes non-transitory medium such as a physical memory device, etc.
• the console 118 further includes a human readable output device(s) such as a monitor, and an input device(s) such as a keyboard, mouse, etc.
• the computer readable storage medium 122 includes instructions 124 for at least a biophysical simulator 126.
• the processor 120 is configured to execute the instructions 124 and/or software that allows the operator to interact with and/or operate the scanner 102 via a graphical user interface (GUI) or otherwise.
• GUI graphical user interface
• the processor 120 may additionally, or alternatively, execute a computer readable instruction(s) carried by a carrier wave, a signal and/or other transitory medium.
• the biophysical simulator 126 is part of another computing system, which is separate from the console 118 and the system 100.
• the other computing system is similar to the console 118 in that it includes a processor, computer readable storage medium, etc., but it does not include software that allows the operator to interact with and/or operate the scanner 102.
• the biophysical simulator 126 is configured to process at least the volumetric image data to perform a biophysical simulation. With respect to FFR, the biophysical simulator determines an FFR index based CCTA image data (or an x-ray angiogram). The FFR index can be displayed via a display monitor, stored, conveyed to another device, etc. As described in greater details below, the biophysical simulator 126 includes one or more feedback loops such as a segmentation feedback loop and/or a boundary condition feedback loop. The feedback loops can be used for training, simulation customization and/or calibration, and/or predictive purposes for individual clinicians, sites, etc.
• the biophysical simulator 126 can be deployed at a clinical site and tuned to individual users and/or the site, e.g., for segmentation of the coronary tree from the CCTA image data (or the x-ray angiogram), or scaling factors for peripheral resistances which control the simulated flow of blood through the coronary arteries. In one instance, this mitigates different outcomes for usage patterns, individual habits, and/or patient populations that vary from site to site. As a consequence, an accuracy of FFR-CT (or x-ray FFR) simulation results from clinician to clinician, site to site, etc. may improve relative to a configuration in which the approach described herein is not utilized and/or the biophysical simulator 126 described herein is omitted.
• FIGURE 2 schematically illustrates an example of the biophysical simulator 126 in connection with FFR-CT.
• the biophysical simulator 126 includes a segmentor 202 with a segmentation feedback loop 204, a boundary condition determiner 206 with a boundary condition feedback loop 208, and a flow simulator 210.
• the segmentation feedback loop 204 is omitted.
• the boundary condition feedback loop 208 is omitted.
• the biophysical simulator 126 receives, as input, CCTA imaging data from the imaging system 100, a data repository (e.g., a radiology information system (RIS), a picture and archiving system (PACS), etc.), and/or other apparatus.
• the segmentor 202 employs a segmentation algorithm to segment the coronary tree from the CCTA imaging data. The segmentation can be performed
• the segmentation includes identifying and/or extracting coronary artery centerlines and/or lumen geometry (e.g., diameter, perimeter, cross- sectional area, etc.) therefrom.
• the segmentation can be based on voxel intensity, object shape, and/or other characteristics.
• FIGURE 3 shows segmentation of a portion of an individual vessel showing opposing walls 302 of the vessel lumen
• FIGURE 4 shows a segmented coronary tree 400.
• the CCTA imaging data is a training set, and experts have already have performed an accurate coronary tree segmentation that results in simulation of an FFR index that matches known "ground truth" invasive FFR measurements, providing a reference segmentation for the training set.
• the segmentor 202 segments the coronary tree from the training set, and a user freely manipulates the coronary tree segmentation with the tools of the segmentor 202.
• the segmentor 202 compares the user adjusted coronary tree segmentation with the reference segmentation.
• the segmentor 202 via the feedback loop 204, provides feedback indicating any differences between the user adjusted coronary tree segmentation and the reference segmentation.
• the feedback may indicate whether a subsequent adjusted coronary tree segmentation is closer to the reference segmentation, a recommendation for improving the segmentation, and/or other information about the segmentation.
• the CCTA imaging data again is the training set.
• the segmentor 202 learns differences between the user adjusted coronary tree segmentation and the reference segmentation and stores the deviations as user-specific calibration data.
• the segmentor 202 utilizes the user-specific calibration data, e.g., to automatically adapt a subsequent user adjusted coronary tree segmentation from patient CCTA imaging data under evaluation or analysis (a non-training data set).
• the segmentor 202 via the feedback loop 204, visually presents an adapted adjusted coronary tree segmentation based on the user- specific calibration data.
• the segmentor 202 may shift one or more points of a segmentation.
• the segmentor 202 can increase or decrease a diameter of a segmented coronary vessel, move a wall of a segmented coronary vessel, etc.
• the user can accept, reject and/or modify the visually presented adapted adjusted coronary tree segmentation.
• the user may also redo the segmentation.
• the user may periodically use the training set (and/or another training set) to update their user- specific calibration data. For instance, over time, the user's ability to create an adjusted coronary tree segmentation that is more accurate relative to the reference may increase with experience. In such an instance, the current user-specific calibration data may overcorrect. For this, the user can process the training set (and/or the other training set), and segmentor 202 can update the user-specific calibration data based on the deviations therefrom. Additionally, or
• the segmentor 202 upon start up or otherwise, may present a training set to the user to update their user- specific calibration data.
• the boundary condition determiner 206 determines boundary conditions for a computational fluid dynamic simulation of blood flow in vessels from the user adjusted coronary tree segmentation and/or the segmentor 202 adapted user adjusted coronary tree segmentation.
• a parametric lumped model is employed.
• the model includes a centerline representation using nonlinear resistances, with elements indicating inflow and outflow boundary conditions, and elements representing tree segment transfer functions, which include a series of linear and nonlinear resistance elements reflecting vessel geometry (e.g., diameter, perimeter, cross-sectional area, etc.) and/or hydraulic effects (e.g., 1-6 in Table 1).
• patient-specific data collected after the FFR-CT simulation is provided to the boundary condition determiner 206.
• data include, but are not limited to, hematocrit, presence/absence of diabetes, acute coronary syndrome, and blood pressure.
• the data can be provided by a user, extracted from an electronic patient record, and/or otherwise retrieved.
• the patient- specific data is used, via the feedback loop 208, to update boundary conditions. For example, invasive FFR measurements for patients who had previously undergone FFR-CT simulation can be used to improve future simulations. Furthermore, documented outcomes, additional biophysical and/or functional measurements may be used to readjust the boundary conditions.
• Hematocrit is a measure of a volume percentage of red blood cells.
• an increased hematocrit means a higher value of the viscosity of blood.
• the viscosity of blood can be adjusted using an empirical curve, e.g., a linear scaling between 40 -45 .
• the presence of diabetes generally means stiffer walls and higher myocardial resistance.
• the corresponding resistance boundary condition can be adjusted, e.g., by adding 10% to the default value.
• this threshold can be increased, e.g., to 0.85, for a patient with acute coronary syndrome (ACS), to ensure that borderline patients are treated.
• ACS acute coronary syndrome
• Additional invasive reference FFR measurements for a particular patient can be used to adapt any model parameter e.g. the myocardial resistance so as to obtain a better match between reference and model prediction (given the current segmentation). This can be done by gradient descent, parameter search, etc.
• Documented patient outcome such as cardiac events or survival data can be used in a similar way to adapt parameters taking the previously obtained model prediction and the medical treatment into account. For example, if a lesion was considered insignificant via a CT-FFR assessment and that lesion caused a major cardiac event, then the assessment can be reconsidered and parameters such as the FFR threshold can be updated to better match the outcome.
• the boundary condition determiner 206 also determines boundary conditions for one or more input parameters. Additionally, or alternatively, for one or more input parameters, the boundary condition determiner 206 also determines boundary conditions for one or more input parameters.
• the boundary condition determiner 206 can also determine boundary conditions for at least a blood pressure values of (X)(+0.Z), where Z represents a tolerance as a percentage such as 1%, 2%, 5%, 10%, 25%, etc. This allows the computing system 118 to compute FFR values for the input parameter as well as a value(s) around the input value.
• the computed FFR values will indicate how the values of a parameter effects the outcome of the FFR-CT simulation.
• a confidence of a parameter value e.g., a measured blood pressure
• a small change in the value has a significant effect on the FFR value
• the user may choose to acquire and use a more accurate value, rather than use the current value.
• the user may proceed with the understanding of how this parameter value effects the FFR value.
• the user may proceed without using this parameter value and/or adjusting boundary conditions affected by this parameter.
• a confidence of a parameter value is high, the user may continue with the value.
• the flow simulator 210 performs a flow simulation with the boundary conditions and generates and outputs FFR values.
• Flow simulations can be done, e.g., using a computational fluid dynamics (CFD) approach and/or other approach.
• CFD computational fluid dynamics
• Examples of computing FFR values are described in US 2015/0092999 Al, filed May 10, 2013, and entitled “Determination of a fractional flow reserve (FFR) value for a stenosis of a vessel," US 2015/0282765 Al, filed October 24, 2013, and entitled “Fractional flow reserve (FFR) index,” which are incorporated herein by reference in their entireties.
• FIGURE 5 illustrates an example method in accordance with an embodiment described herein.
• a coronary vessel is segmented from a training set of CCTA imaging data.
• a user input indicative of an adjustment to the segmentation is received and applied to the segmented vessel, producing a user adjusted coronary vessel segmentation.
• the user adjusted coronary vessel segmentation is compared with a reference vessel segmentation for the training set.
• a difference between the segmentations is visually presented.
• the difference can be graphical and/or numerical.
• This method is well- suited for coronary tree segmentation training.
• FIGURE 6 illustrates another example method in accordance with an embodiment described herein.
• a coronary tree is segmented from a training set of CCTA imaging data.
• a user input indicative of an adjustment to the segmentation is received and applied to the segmented tree, producing a user adjusted coronary tree segmentation.
• the user adjusted coronary tree segmentation is compared with a reference tree segmentation for the training set of cardiac imaging data.
• a deviation therebetween is stored as a user-specific calibration.
• a coronary tree is segmented from CCTA imaging data of a patient under evaluation.
• a user input indicative of an adjustment to the segmentation is received and applied to the segmented tree, producing a user adjusted coronary tree segmentation.
• the user-specific calibration is applied to the user adjusted coronary vessel segmentation, producing an adapted user adjusted coronary tree segmentation for the patient.
• an FFR index is generated using the adapted user adjusted coronary tree segmentation.
• FIGURE 7 illustrates another example method in accordance with an embodiment described herein.
• a coronary tree is segmented from CCTA imaging data of a patient.
• the coronary tree is adapted as described in connection with FIGURE 6.
• boundary conditions are determined based on the coronary tree.
• FFR values are determined with the boundary conditions.
• the boundary conditions are updated based on patient specific and/or other data.
• the above may be implemented by way of computer readable instructions, encoded or embedded on computer readable storage medium, which, when executed by a computer processor(s), cause the processor(s) to carry out the described acts. Additionally, or alternatively, at least one of the computer readable instructions is carried by a signal, carrier wave or other transitory medium, which is not computer readable storage medium. Furthermore, it is to be appreciated that the ordering of the acts is not limiting. As such, other orderings are contemplated herein. In addition, one or more acts may be omitted and/or one or more additional acts may be included.
• a computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems. Any reference signs in the claims should not be construed as limiting the scope.

Landscapes

• Health & Medical Sciences (AREA)
• Engineering & Computer Science (AREA)
• Medical Informatics (AREA)
• Public Health (AREA)
• Life Sciences & Earth Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Pathology (AREA)
• Biomedical Technology (AREA)
• Physics & Mathematics (AREA)
• Epidemiology (AREA)
• Primary Health Care (AREA)
• Databases & Information Systems (AREA)
• Data Mining & Analysis (AREA)
• Molecular Biology (AREA)
• Animal Behavior & Ethology (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Radiology & Medical Imaging (AREA)
• Veterinary Medicine (AREA)
• Surgery (AREA)
• Biophysics (AREA)
• Heart & Thoracic Surgery (AREA)
• Computer Vision & Pattern Recognition (AREA)
• General Physics & Mathematics (AREA)
• Theoretical Computer Science (AREA)
• Quality & Reliability (AREA)
• Optics & Photonics (AREA)
• Cardiology (AREA)
• Apparatus For Radiation Diagnosis (AREA)
• Image Analysis (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=61952704

Family Applications (1)

Country Status (5)

Families Citing this family (18)

Family Cites Families (16)

• 2018
  • 2018-04-06 CN CN201880023384.5A patent/CN110574121B/zh active Active
  • 2018-04-06 JP JP2019554672A patent/JP7313284B2/ja active Active
  • 2018-04-06 US US16/500,245 patent/US11195278B2/en active Active
  • 2018-04-06 WO PCT/EP2018/058885 patent/WO2018185298A1/en not_active Ceased
  • 2018-04-06 EP EP18717015.4A patent/EP3607558A1/en not_active Withdrawn

Also Published As

Similar Documents

Legal Events